The present invention is in the field of laser marking on diamonds.
Marking on diamonds is required for such purposes as their sawing or indicia stamping (identification and quality marks, etc).
For marking various indicia on a diamond surface, different laser marking techniques are known to be employed as suggested, for example, in U.S. Pat. Nos. 5,410,125, 5,573,684 and EP 0 054 840.
In order to obtain durable marking with the known laser marking techniques, a high level of laser energy density is used, which may adversely affect the value of the diamond by heating and vaporizing a portion of its body and/or causing microcracks. The required graphics of the indicia is achieved through the employment of various means including complex optical axis tilting, numerous X-Y tables, partial masking, etc.
For sawing purposes, predetermined xe2x80x98sawing linesxe2x80x99 are marked on diamond surfaces and actual sawing is performed in accordance with these lines. The marks are nowadays drawn manually, with ink dots representing the lines. Positions of the dots are chosen by eye judgment either alone, or aided by various CAM devices such as the DiaExpert 2000 by Sarin Technologies Ltd. in Israel.
According to one aspect of the present invention, there is provided an attachment to 3D diamond mapping apparatus, for diamond laser marking. The 3D mapping apparatus is capable of mapping a diamond whose surface is to be marked with a marking pattern, and of determining a succession of points representing said pattern. The attachment comprises a laser source with its associated focusing optics for emitting a focused laser beam along an optical path which extends between said source and a marking position on said surface of the diamond and a beam orientation system to move said path relative to the diamond and to thereby bring it to said marking position. The mapping apparatus and the attachment constitute, at least in operation, an integral mapping and marking system whose computer means calculates coordinates of each point of the marking pattern and manipulates said beam orientation system to direct the laser beam successively to said points.
In accordance with another aspect of the present invention, there is provided a method of permanent laser marking allowing the use of lower laser power by means of coating the diamond prior to its marking and performing the marking through or on the coating.
The present invention, in accordance with both aspects thereof, can be used for performing any marking on any diamonds, but it is particularly advantageous for diamond CAM laser marking of xe2x80x98sawing linesxe2x80x99.